Device for coaxial connection

ABSTRACT

A device for a coaxial connection that is intended to connect a coaxial cable ( 6 ) to the conductive pattern ( 3   a ) of a circuit board and contains an outer conductor ( 1 ) with an inner conductor ( 4 ) that is insulated relative thereto. The device contains a longitudinal coupling element ( 8 ) that is axially slidably mounted in a recess ( 4   a ) in the inner conductor ( 4;6   a ) and arranged so as to be in capacitive communication with the inner conductor ( 4;6   a ) and connected to the conductive pattern ( 3   a ). A layer ( 7 ) of insulating material is arranged between the coupling element ( 8 ) and the recess ( 4   a ).

CROSS-REFERENCE TO RELATED APPLICATIONS

The application is a 35 U.S.C. §371 National Phase Filing of PCTapplication PCT/SE01/02720, which claims priority to Swedish applicationSE 0100056-1, filed Jan. 9, 2001.

BACKGROUND OF THE INVENTION

This invention concerns a device for a coaxial connection that isintended for connecting a coaxial cable to the conductive pattern of acircuit board, and contains an outer conductor with an inner conductorthat is insulated relative thereto.

A coaxial connection (coaxial connector) consists of an inner conductorand a connector housing that is insulated relative thereto. When theconnector is connected to a circuit board, the inner conductor of theconnector is normally soldered to the conductive pattern of the circuitboard, while the connector housing is arranged in contact with theenclosure that surrounds the circuit board.

Thermomechanical problems can arise in such a coaxial connector as aresult of differing expansion constants between the inner conductor andconnector housing of the connector. These problems manifest as cracksthat form in the circuit board conductive pattern and the solder jointsby means of which electrical contact is established between the cableand the conductive pattern, resulting in turn in electricalinterruptions.

SUMMARY OF THE INVENTION

The purpose of this invention is to provide a coaxial connector of thetype described above in which the risk of electrical interruptionsresulting from variations in thermal expansion is substantially reduced.This purpose is achieved in that the device contains a longitudinalcoupling element that is axially slidably mounted in a recess in theinner conductor and arranged so as to be in capacitive communicationwith the inner conductor and connected to the conductive pattern, and inthat a layer of insulating material is arranged between the couplingelement and the recess.

In an application of the invention, the device according to theinvention will exhibit the features described in the characterizingsections of claims 2-5.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in detail below with reference to theaccompanying drawing, in which FIG. 1 shows a schematic section of acoaxial connector according to the invention.

FIG. 2 shows a schematic section of an alternative embodiment of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1, 1 designates a connector housing made of an electricallyconductive material, preferably a metal, that is arranged in contactwith a circuit board box 2, in which is mounted a circuit board 3 with aconductive pattern 3 a. The circuit board box 2, which consists of anelectrically conductive material, holds the circuit board 3 in place andfunctions as a shield for incoming and outgoing radiation. The connectorhousing 1 contains an inner conductor 4 and, between this and theconnector housing 1, an insulating body 5 of an electricallynon-conductive material.

6 generally designates a coaxial cable that is connected to the coaxialconnector in the usual manner and contains a center conductor 6 a,insulation 6 b and a shield 6 c that is electrically connected with theconnector housing, and an insulating jacket 6 d. In one alternativeembodiment (not shown), the coaxial cable lacks the insulating jacket 6d.

In the embodiment depicted, the insulating body 5 with the innerconductor 4 slides outside of the connector housing 1 and extendsthrough an opening 2 a in the circuit card box 2. Alternatively, thecircuit board can extend through the opening 2 a instead of theinsulating body 5 with the inner conductor doing so.

According to the invention, there is in the center conductor 4 a recess4 a in which is fixedly mounted a socket 7 of an electricallynon-conductive material. A longitudinal coupling element 8 made of anelectrically conductive material, and of such length that it protrudesoutside of the insulation body 5 even when it is entirely inserted intothe recess 4 a, is axially slidably mounted in the socket 7 andconnected at its protruding end to the conductive pattern 3 a,preferably by means of a solder joint 9. The coupling element 8 may ofcourse be connected to the conductive pattern 3 a in some other mannerknown to one skilled in the art, such as gluing or welding.

In an alternative embodiment of the invention (not shown), the socket 7is mounted on the coupling element 8 rather than inside the recess 4 a.

The coupling element 8 is in capacitive communication with the innerconductor 4, while simultaneously being able to move somewhat relativethereto in order to absorb thermally induced relative movement betweenthe inner conductor 4 and the connector housing 1. The coupling elementcan also absorb some relative movements between the circuit board 3 andthe circuit board box 2.

Because the coupling element is in capacitive communication with theinner conductor 4, the coaxial connector also functions as a dc block,i.e. it prevents low-frequency current from passing.

In an alternative embodiment of the device according to the invention,which is shown in FIG. 2, the coaxial cable 6 is connected directly tothe circuit board 3. In this case the recess 4 a is made directly in thecenter conductor 6 a of the cable 6, and the coupling element 8 is thusin capacitive communication with the center conductor 6 a. The shield 6c of the cable 6 is arranged in contact with the opening 2 a in thecircuit board box 2 and electrically connected thereto.

It will be apparent to one skilled in the art that, within the limits ofthe idea of the invention, the coupling element 8 can be made longenough to reach, via an opening in the ground plane of a circuit board,a conductive pattern applied to the opposite side of the circuit board.

1. A device for a coaxial connection that is intended to connect acoaxial cable to the conductive pattern of a circuit board and containsan outer conductor with an inner conductor that is insulated relativethereto, characterized in that the device contains a longitudinalcoupling element that is axially slidably mounted in a recess in theinner conductor and arranged so as to be in capacitive communicationwith the inner conductor and connected to the conductive pattern, and inthat a layer of insulating material is arranged between the couplingelement and the recess.
 2. A device according to claim 1, characterizedin that the outer conductor is a connector housing belonging to theconnector.
 3. A device according to claim 1, characterized in that theouter conductor is the shield of a coaxial cable.
 4. A device accordingto claim 1, characterized in that the insulating layer is a socket thatis fixedly mounted in the recess.
 5. A device according to any of thepreceding claims, characterized in that the coupling element isconnected to the conductive pattern by means of soldering.
 6. The deviceof claim 3 wherein the outer conductor further comprises a connectorhousing.
 7. The device of claim 3 wherein the coaxial cable lacks aninsulating jacket.
 8. The device of claim 1 wherein the outer conductorcomprises a connector housing.
 9. The device of claim 8 wherein theinsulating layer and inner conductor slide outside of the connectorhousing to contact the conductive pattern.
 10. The device of claim 1wherein the circuit board is contained within a circuit card box havingan opening proximate to the conductive pattern, wherein the insulatinglayer and inner conductor extend through the opening, and wherein theinner conductor contacts the conductive pattern inside the circuit cardbox.
 11. The device of claim 1 wherein the circuit board is containedwithin a circuit card box having an opening proximate to the conductivepattern, wherein at least a portion of the circuit board carrying atleast a portion of the conductive pattern extends through the opening,and wherein the inner conductor contacts the conductive pattern exteriorto the circuit card box.
 12. The device of claim 1 wherein the couplingelement is of such a length that a portion of the coupling elementprotrudes outside of the insulating material even when the couplingelement is inserted within the insulating material.
 13. The device ofclaim 1 wherein the coupling element is connected to the conductivepattern by gluing.
 14. The device of claim 1 wherein the couplingelement is connected to the conductive pattern by welding.
 15. Thedevice of claim 1 wherein the coupling element is slidably mountedaround the inner conductor, wherein the inner conductor is positioned ina recess within the coupling element, and wherein the insulatingmaterial is mounted on the inner surface of the recess.
 16. The deviceof claim 1 wherein the coupling element moves relative to the innerconductor to absorb thermally-induced relative movement between thecoupling element and inner conductor.
 17. The device of claim 10 whereinthe coupling element moves relative to the inner conductor to absorbthermally-induced relative movement between the circuit board and thecircuit card box.
 18. The device of claim 1 which further acts as a dcblock.
 19. The device of claim 1 wherein the outer conductor and innerconductor insulated relative thereto comprise a coaxial cable having acenter conductor, and wherein the recess is arranged within the centerconductor.
 20. The device of claim 1 wherein the conductive element hasa length sufficient to traverse the thickness of a circuit board toconnect to a conductive pattern on an opposite side of the circuitboard.